"Twilight" hunk Kellan Lutz has shown off his buff bod in a new Calvin Klein campaign. In the ad for the company's new men's fashion range for underwear, Calvin Klein Underwear X Elements, the 25-year-old actor is pictured in nothing but a green underwear.

Kellan was accompanied by "True Blood" star Mehcad Brooks, tennis player Fernando Verdasco and Japanese athlete Hidetoshi Nakata who all stripped to their Calvin Klein underwear, each representing a different element - earth, fire, air, and water.

And now, the company has invited men around the world to share their thoughts about the X briefs on YouTube. "Calvin Klein X Underwear launched with Kellan Lutz, Mehcad Brooks, Fernando Verdasco and Hidetoshi Nakata. Now X is going global... all through your webcams," a spokesperson for Calvin Klein said.

"X Marks the World lets you look into webcams of guys from all over Europe, Africa, North America, South America and Asia," the spokesperson added. "And it's not just a one-way conversation. Calvin Klein X Underwear is inviting men around the world to upload and share on YouTube as well. No set-up. No acting. No script. Just a guy, a webcam and his 'X'."